The invention relates to a fixing device for a headrest, particularly to a fixing device for a headrest for fixing a headrest stay at a predetermined position, so that the headrest is not adjustable.
Regulations on height requirements for headrests (Federal Motor Vehicle Safety Standard FMVSS202A) and the like require a headrest to be fixed to not drop from a use position.
In general, a technique for fixing the headrest is already known. For example, FIGS. 8 and 9 show one example thereof. FIG. 8 is an exploded perspective view of a guide lock showing a conventional example, and FIG. 9 is a sectional view of major parts by the section line A-A of FIG. 8.
As shown in FIGS. 8 and 9, in the conventional technique, a headrest guide (not shown) of a headrest pillar 120 is arranged in a backrest frame. The headrest pillar 120 is fixed to this headrest guide at a predetermined position by way of a dedicated guide lock 130 and a lock spring 140.
That is, a groove portion 121 that engages with the lock spring 140 is formed in the headrest pillar 120, and a retaining portion 141 is formed in the lock spring 140 to fit on the outer peripheral side of the guide lock 130. Part of this retaining portion 141 is formed as a curved portion 142 biasing in the inner direction of the guide lock 130.
A cutout 131 is formed at a predetermined position of the hollow guide lock 130 formed into a predetermined shape. The headrest pillar 120 is inserted into the guide lock 130, and the cutout 131 of the dedicated guide lock 130 is matched with the groove portion 121 of the headrest pillar 120. Then, by installing the curved portion 142 of the lock spring 140 in this cutout 131, the lock spring 140 extends on the inner side of the guide lock 130 from the cutout 131 and fits into the groove portion 121 of the headrest pillar 120 which is thus fixed.
It should be noted that in FIG. 8, the reference numerals 132 denote guides for eliminating backlash between the guide lock and the headrest guide (not shown) when the headrest guide is rectangular and the guide lock 130 is cylindrical.
There are various proposed techniques regarding a headrest capable of adjusting height of the position-adjustable headrest (for example, refer to Japanese Patent Application Publication No. 2008-119398 (“the '398 Publication) (claim 1, FIGS. 1, 2)).
The '398 Publication discloses a headrest, including a headrest support formed by a head portion, a neck portion, and a trunk portion, and supported by a bracket provided in a seat frame of a vehicle, a through hole provided in this headrest support, the through hole for fitting a headrest stay provided with a height-fixing and retaining first cutout and a height-adjusting second cutout, and an operation button capable of appearing from and disappearing into an insertion hole of the head portion of the headrest support. In this technique, a locking piece provided with a projection to be locked onto the first cutout or the second cutout is provided in the operation button of the headrest, and a spring serving for return of this locking piece is provided. By locking the projection onto the first cutout or the second cutout by operating the locking piece, the headrest stay is settable at a predetermined position. The first cutout and the second cutout are provided by depressing a surface side of the headrest stay. Such a headrest for retaining the headrest stay, height-fixing, and height-adjusting is disclosed.
However, in the above conventional technique shown in FIGS. 8 and 9, there is a need for using the dedicated lock spring 140 with the dedicated guide lock 130 for the fixing type headrest guide. In the above conventional technique, there is a need for adjusting the height to predetermined height at first, and then fixing the headrest at a height position thereof. Although the conventional technique complies with predetermined regulations, the guide lock of the headrest should be exposed before adjustment in order to fix the headrest at a position matching with a user's head within a range complying with the regulations. Thus, there is a disadvantage that a fixing position cannot actually be adjusted after assembling is done.
Further, the technique shown in the '398 Publication is a technique for position-adjusting or retaining, that is, not a technique for fixing the headrest in such a manner that the headrest does not drop from the use position as a so-called fixed fitting but a technique for adjusting. Thus, there is a need for a spring or the like as a returning mechanism, so that the number of parts is increased, and moreover, there is a need for using a specific guide lock instead of a normal guide lock (the headrest support in the '398 Publication).